The complexity of a cellular handset has increased dramatically over recent years because of increased band proliferation as the world aggressively moves to 4G (fourth generation) mobile telephone technology. The size of an RF component might be its most important feature now.
The number of supported bands in high-end smartphones now exceeds twenty (20). Most of these bands require their own duplex filter, which means the size of an RF component is one of the most (if not THE most) important feature. In most cases, RF component suppliers are competing for the same socket and are given the same footprint requirement. It is up to suppliers to determine how to budget the space they have available. If they use too much area on the power amplifier, they will need to use smaller, lower performance filters and surface mount devices (SMDs). If they choose to use premium, higher performance filters, the power amplifier area must be reduced. Thus, there remains a need to the ability to cover all of the cellular handset bands in a single power amplifier core.
The present disclosure relates to a power amplifier architecture design that covers all of the cellular handset bands from 698-915 MHz in a single power amplifier core. The disclosed power amplifier architecture is designed to simultaneously achieve broad bandwidth, high performance, compact size, and low cost with almost no compromise in any of these features. In spite of its small size and broad bandwidth, the differential power amplifier disclosed herein maintains very high performance and is extremely low in cost.